Editing the world's time speed is something I find myself doing often. I like longer days and the increased down time between days with the following longer nights.

One issue I found with reducing the speed at which time passes is that the burn time of fuel for your firepit doesn't scale with time speed, which massively increases the fuel expenditure to keep warm during the winter. There are already mods of this brand which increase fuel burn time but I couldn't decide which to use, so I made my own.

Currently I have two variants, x2 (intended for worlds with timespeed=30) and x3 (intended for worlds with timespeed=20).
I did not edit cooking times as hunger also doesn't scale with the set time speed. That may be a project for another mod.
If you wish for more variants, just ask in the comments. It's not hard to do, just long and boring so it's better if I made more on-demand.